With the development of science and technology and economy, people are increasingly pursuing visual enjoyment. An omnidirectional holographic projection system, which is formed by a plurality of half-transmitting mirrors based on the imaging theory of light reflection, has been applied in some fields. However, the conventional virtual imaging devices with a large size are not easy to carry, and have poor portability. Besides, the conventional virtual imaging devices cannot be disassembled conveniently once having been assembled, and thus are prone to collision during transportation.